Bending And Shear Ultimate Capacity Of Steel Reinforced Concrete Column

As an important vertical component in reinforced concrete structure,aframecolumn bears both the vertical loads and lateral loads. The safety of the structureis directly affected by the mechanical performance and plastic deformation capacity.Previous experience of earthquake damage shows that if the project was improperlyhandled, the frame columns are prone to fragile shear failure, which can easily cause asudden drop of horizontal bearing capacity and an inadequate plastic deformationcapacity, leading to the structural collapse. With the appearance of large numbers ofhigh-rise buildings, steel reinforced concrete column (hereafter referred to as SRCcolumn) has been widely used because of its high stiffness, high bearing capacity andgood deformation capacity. The ultimate bearing capacity and deformation ability ofSRC column under seismic action is studied, especially the basic rule of plasticdeformation ability, by analyzing the existing static and seismic performance test data ofSRC column. Then, the existing models of the ultimate bearing capacity of bending andshear analysis are analyzed and evaluated. Also,the design methods in differentspecifications, including “Composite structure design code (draft)”, are comparativelyanalyzed. Based on this, some rationalization suggestions to engineering application ofSRC column are proposed in this thesis.The main jobs of this study are as follows:①The existed test results of SRC column are collected and corresponding databasewas established, including the eccentric loading data under static loads and the seismicperformance loading data under cyclic loads;②The main influence parameters of ultimate bearing capacity and plasticdeformation and their regularities are studied in detail, where the analysis of thecombined influence of the axial compression ratio, stirrup ratio and shear span ratio toshort columns are mainly focused;③The calculation methods of flexural strength of SRC columns is comparativelyanalyzed by using the superposition method and the plane section assumption methodfor bending capacity analysis;④By analyzing the modeling method of beam mechanism-arch mechanism whichwas established by Minami Koichi, the shear capacity of steel reinforced concretecolumn is predicted, meanwhile advantages and disadvantages of modeling method is analyzed and evaluated;⑤The standard value the predicted results calculated by the calculation method inChina code “Composite structure design code (draft)”and in Japanese code “Steelreinforced concrete calculation standard and commentarycode (the third revised edition)”are comparatively analyzed with experimental data and predicted shear capacity valueobtained from Minami Koichi’s method. Then the applicability of the formula of shearspecification is evaluated and some amendments are proposed.The main conclusions of this thesis are as follows:①Both the simple superposition method and the plane section assumptionmethod for ultimate flexural capacity are both applicable for predicting the bendingbearing capacity of bending failure members, but the calculated result of plane sectionassumption is more accurate;②Use beam mechanism-arch mechanism analysis model to predict the ultimateshear capacity of steel reinforced concrete column is reasonable. Especially, when thecolumn is under high axial compression ratio,the predicted ultimate shear capacity byusing this modeling method is also accurate;③Compared with experimental values,predictive values of shear resistanceobtained from the Chinese code “Composite structure design code (draft)”, the meanand the standard deviation is1.7and0.16; by using Japanese code “Steel reinforcedconcrete calculation standard and commentary code (the third revised edition)”, themean and the standard deviation is1.4and0.12; by using Minami Koichi’s method, themean and the standard deviation is1.25and0.1. Thus, the Minami Koichi’s method isthe most reasonable one to predict shear bearing capacity, who has the thorough studyand perfect system of the shear mechanism, and is quite worthy of our standardreference.